Variable orifice rotary valves for controlling gas flow

ABSTRACT

Gas flow control valves comprising a valve housing including a cylindrical interior passage, and a housing opening extending from the interior passage through the housing. The gas flow control valve further comprises a cylindrical rotary valve element including a sidewall, and a rotary valve element opening extending through the sidewall. The valve element is rotatably received within the interior passage of the valve housing, such that the housing opening may be selectively aligned with the rotary valve element opening, and an area of overlap of the housing opening and the valve element opening may be varied by rotating the valve element within the interior passage of the valve housing.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the U.S. National Stage of International ApplicationNo. PCT/US2012/025062, filed Feb. 14, 2012, which claims priority fromU.S. Provisional Application Ser. No. 61/442,915, filed Feb. 15, 2011,the entire contents of each of which are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

The present disclosure relates to valves for regulating or controllingthe flow of gases.

BACKGROUND

Potential drawbacks to known valves include limited ability to i)provide fine control over the flow restriction; ii) provide relativelylinear control of the flow; iii) achieve fast response time from fullyclosed to fully open without excessive power consumption; iv) be easilycontrolled electronically; v) control flow over a very wide range offlow rates; vi) function without lubrication; vii) in ventilationapplications involving blowers, enable diversion of airflow to anexhaust port when the valve is closed, and viii) control flows at verylow pressures, such as in ventilation applications, due to the size ofthe orifice opening required.

Two types of known valves are globe valves and piston valves. Thesevalves are common, but suffer from a few problems, including size, slowresponse time, and high restriction even for low pressure drops, whichcreates a high pressure drop at low flows. Specifically, for ventilatorapplications, the same valve cannot be used for adult patients as forneonates, because the flow ranges are very different and the resolutionof control at low flow rates is low.

Other types of known valves are sliding valves and other rotating valvessuch as plug valves, ball valves, and butterfly valves. These valvessuffer from slow response time and imprecise flow control. They are goodfor applications requiring a simple on/off flow control, but their flowrestriction is non-linear as the valve opens and closes. They are thusunable to provide proportional flow control. Another problem with thesevalves is that, usually, in order to enable complete sealing theyrequire lubrication for the moving parts.

SUMMARY

The various embodiments of the present valves have several features, nosingle one of which is solely responsible for their desirableattributes. Without limiting the scope of the present embodiments asexpressed by the claims that follow, their more prominent features nowwill be discussed briefly. After considering this discussion, andparticularly after reading the section entitled “Detailed Description,”one will understand how the features of the present embodiments providethe advantages described herein.

One embodiment of the present gas flow control valves comprises a valvehousing including a cylindrical interior passage, and a housing openingextending from the interior passage through the housing. The gas flowcontrol valve further comprises a cylindrical rotary valve elementincluding a sidewall, and a valve element opening extending through thesidewall. The valve element is rotatably received within the interiorpassage of the valve housing, such that the housing opening may beselectively aligned with the valve element opening, and an area ofoverlap of the housing opening and the valve element opening may bevaried by rotating the valve element within the interior passage of thevalve housing.

In certain embodiments, the housing opening and the valve elementopening comprise a first housing opening and a first valve elementopening, respectively, and the embodiments further comprise a secondhousing opening extending from the interior passage through the housingand a second valve element opening extending through the sidewall.

In certain embodiments, the first and second valve element openings arecircumferentially spaced from one another so that when the first housingopening and the first valve element opening are partially or fullyaligned with one another the second housing opening and the second valveelement opening are not even partially aligned with one another, andvice versa.

In certain embodiments, the first and second valve element openings arecircumferentially spaced from one another so that rotation of the valveelement in a first direction within the housing gradually increases anarea of overlap between first valve element opening and the firsthousing opening while gradually decreasing an area of overlap betweensecond valve element opening and the second housing opening, androtation of the valve element in a second direction opposite the firstdirection within the housing gradually decreases an area of overlapbetween first valve element opening and the first housing opening whilegradually increasing an area of overlap between second valve elementopening and the second housing opening.

In certain embodiments, the first and second valve element openings areaxially spaced from one another.

In certain embodiments, the first housing opening and the second housingopening are differently sized from one another, and the first valveelement opening and the second valve element opening are differentlysized from one another.

Certain embodiments further comprise a third housing opening extendingfrom the interior passage through the housing and a third valve elementopening extending through the sidewall.

In certain embodiments, at least one of the valve element opening andthe housing opening is tapered.

In certain embodiments, the valve element opening comprises a firstvalve element opening, and the embodiments further comprise a secondvalve element opening extending through the sidewall, wherein the firstand second valve element openings are located at a same axial positionalong a length of the valve element.

In certain embodiments, the axial position of the first and second valveelement openings corresponds to an axial position of the housing openingalong a length of the housing.

In certain embodiments, the valve element is open at a first end andclosed at a second end opposite the first end.

In certain embodiments, the valve element is closed at both ends.

In certain embodiments, the housing opening is much larger than thevalve element opening so that rotating the valve element within theinterior passage of the valve housing enables flow through the valveelement opening to be blocked, and also enables the valve element tochange a direction of flow outward from the housing opening.

In certain embodiments, the valve element and/or the interior passage ofthe valve housing comprises a low-friction polymer.

In certain embodiments, the valve element comprises graphite.

In certain embodiments, the interior passage of the valve housingcomprises glass.

Certain embodiments further comprise a first pair ofdiametrically-opposed alignment apertures in the sidewall of the valveelement.

Certain embodiments further comprise a second pair ofdiametrically-opposed alignment apertures in the housing positioned toalign with the first pair of diametrically-opposed alignment apertureswhen the valve element is in a home orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments of the present valves now will be discussed indetail with an emphasis on highlighting the advantageous features. Theseembodiments depict the novel and non-obvious valves shown in theaccompanying drawings, which are for illustrative purposes only. Thesedrawings include the following figures, in which like numerals indicatelike parts:

FIG. 1A is a perspective view of a rotary valve element or cylinderemployed in a variable orifice valve in accordance with one embodimentof the present disclosure, showing the inlet and the tapered outlet slotof the cylinder;

FIG. 1B is a perspective view of the cylinder of FIG. 1A, showing thebypass orifice of the cylinder;

FIGS. 2A, 2B, and 2C are elevational views of the cylinder of FIGS. 1Aand 1B, showing the cylinder in its several rotational positions;

FIG. 3 is a top perspective view of a valve housing in accordance withone embodiment of the present disclosure;

FIG. 4A is a top plan view of a valve in accordance with one embodimentof the present disclosure, the valve comprising the cylinder of FIG. 1Adisposed within the valve housing of FIG. 3, showing the cylinder in afirst position defining a closed variable outlet orifice closed and anopen bypass port;

FIG. 4B is a top plan view of the valve of FIG. 3, showing the cylinderin a second position defining a partially-opened variable outlet orificeand a closed bypass port;

FIG. 5 is another perspective view of the cylinder of FIGS. 1A and 1B;

FIG. 6 is a perspective view of an alternative embodiment of the valvehousing;

FIGS. 7A, 7B, and 7C are perspective views of a variable orifice flowcontrol valve incorporating the housing of FIG. 6, showing the valve infirst, second and third operational positions, respectively;

FIG. 8 is a perspective view of a rotary valve element or cylinder foruse in a variable orifice valve in accordance with a second embodimentof the present disclosure;

FIG. 8A is a perspective view of a rotary valve element or cylinder foruse in a variable orifice valve in accordance with an alternativeembodiment of the present disclosure;

FIGS. 9 and 10 are perspective views of a variable orifice flow controlvalve in accordance with an alternative embodiment of the presentdisclosure, showing the valve in two operational positions;

FIG. 11 is a perspective view of a selector cylinder used in an exampleembodiment of a selector module that may advantageously be used with thevalve of FIGS. 9 and 10;

FIG. 12 is a perspective view of a housing in which the selectorcylinder of FIG. 11 is installed;

FIGS. 13-15 are perspective views of an example embodiment of a selectormodule comprising the selector cylinder of FIG. 11 and the housing ofFIG. 12, showing the several operational positions of the module;

FIG. 16 is a perspective view of a selector module in use in conjunctionwith the valve of FIGS. 9 and 10;

FIG. 17 is an elevational view of a rotational valve element or cylinderfor use in a variable orifice flow control valve in accordance withanother embodiment of the present disclosure;

FIG. 18 is a perspective view of a housing in which the cylinder of FIG.17 is installed to form a valve in accordance with this embodiment;

FIGS. 19-21 are perspective views of a valve in accordance with thisembodiment of the present disclosure, showing the valve in its severaloperational positions;

FIG. 22 is a perspective view of a variable orifice flow control valvein accordance with another embodiment of the present disclosure;

FIGS. 23A and 23B are elevational views of the valve of FIG. 22, showingthe valve in its several operational positions;

FIG. 24 is an elevational view of a variable orifice flow control valvein accordance with another embodiment of the present disclosure;

FIG. 25 is a perspective view of a first portion of a housing inaccordance with another embodiment of the present disclosure;

FIG. 26 is a perspective view of a second portion of the housing of FIG.25;

FIG. 27 is a perspective view of a cylinder for use with the housing ofFIG. 25; and

FIG. 28 is a perspective view of the cylinder of FIG. 27.

DETAILED DESCRIPTION

The drawings and their descriptions may indicate sizes, shapes andconfigurations of the various components. Such depictions anddescriptions should not be interpreted as limiting. Alternative sizes,shapes and configurations are also contemplated as within the scope ofthe present embodiments. Also, the drawings, and their writtendescriptions, indicate that certain components of the apparatus areformed integrally, and certain other components are formed as separatepieces. Components shown and described herein as being formed integrallymay in alternative embodiments be formed as separate pieces. Further,components shown and described herein as being formed as separate piecesmay in alternative embodiments be formed integrally. As used herein theterm integral describes a single unitary piece.

The present variable orifice valves are configured and operable toregulate or control the flow of gases. In one example application, thevalves can control the flow of respiratory gas (e.g. air,oxygen-enriched air, or oxygen) through a medical ventilator to delivera desired pressure and/or volumetric flow rate to a patient. Moregenerally, the valves disclosed herein have numerous applications forcontrolling the flow of any gas(es). For simplicity, the followingdiscussion will assume that the gas flowing though the valve is air.Accordingly, the following discussion should not be considered limitinginsofar as it focuses on applications for controlling gas flow.

FIGS. 1A-5 illustrate one embodiment of a variable orifice gas flowcontrol valve 10 (FIGS. 3, 4A, 4B) in accordance with the presentdisclosure. The description of FIGS. 1A-5 relates to a medicalventilator application for the valves in accordance with the presentdisclosure. However, the valves disclosed herein are not limited to amedical ventilator application. They may be used in a variety of otherapplications, including, without limitation, mixing a plurality ofgases, controlling flow in a vehicle heating/cooling system, etc.

The valve 10 includes a generally cylindrical rotary valve element or“cylinder” 30 that is rotatably received within a housing 32 (FIGS. 3,4A, 4B). With reference to FIGS. 1A, 1B, 2A, 2B, and 2C, the cylinder 30is hollow, having an opening forming a gas inlet 34 at a first end, andclosed at a second end 36 opposite the inlet 34. A recess or fitting 38in the closed second end 36 receives a motor shaft (not shown) to rotatethe cylinder 30 within the housing 32. In certain embodiments, thecylinder 30 may be made of graphite. However, in other embodiments thecylinder 30 may be any suitable material, such as a suitable polymer,especially a durable, low-friction polymer such aspolytetrafluoroethylene (PTFE).

Adjacent the inlet 34, the sidewall of the cylinder 30 includes a firstopening, cutout, or slot 40. The first opening, cutout, or slot 40extends around a portion of the cylinder's circumference, and has atapering width measured in the longitudinal direction of the cylinder30. The tapered cutout 40 provides a variable orifice for a gas outletport, as described further below. In the illustrated embodiment, thetaper of the cutout 40 has a linear profile. However, in alternativeembodiments the taper may have any profile, such as exponential,logarithmic, parabolic, etc. In still further embodiments, the firstcutout 40 may not be tapered, and may be, for example, rectangular orany other shape. For simplicity, the first cutout 40 is referred to as atapered cutout 40, but this terminology should not be interpreted aslimiting.

In some embodiments of the valve in accordance with this disclosure, afirst pair of diametrically-opposed alignment apertures 42 mayoptionally be provided in the sidewall of the cylinder 30, such asbetween the cutout 40 and the second end 36. The alignment apertures 42define a “home” position for the valve. A beam of light 39 from a source41 external to the valve 10 can be directed through both alignmentapertures 42 to a photo-detector 43 to determine that the cylinder 30 isin the “home” orientation, as shown in FIG. 2B, which shows anorientation of the cylinder 30 in which the alignment apertures 42 facethe source 41 and the photo-detector 43. The structure and/or size ofthe alignment apertures 42 may vary according to accuracy requirements.In other embodiments, alternative means of homing may be used, such as amagnetic (Hall effect) sensor, a photointerrupter, an encoder with azero position, etc.

The sidewall of the cylinder 30 further includes a second opening,cutout, or slot 44, which may, in some embodiments, be configured as arectangle. In certain embodiments, the second opening 44 of the cylinder30 forms an exhaust or bypass opening together with a correspondingopening (described below) in the housing, as described further below. Insome applications there may be no need for an exhaust or bypass opening.Thus, although the second opening 44 is referred to herein as an exhaustopening 44, that terminology should not be interpreted as limiting.Also, in some applications the size or shape of the exhaust opening 44may vary, and may be, for example, non-rectangular. The exhaust opening44 could be, for example, tapered.

With reference to FIG. 3, the housing 32, in one embodiment, may be agenerally rectangular parallelepiped including a cylindrical passage 46for receiving the rotatable cylinder 30. In other embodiments, the shapeof the housing 32 may be other than the example configuration shown inthe drawings. The passage 46 is dimensioned to prevent substantialleakage of gas between the cylinder 30 and the housing walls definingthe passage 46. In certain embodiments, the passage 46 may include alining (not shown) to reduce friction with the rotatable cylinder 30. Incertain embodiments, the lining may be glass, and may fit in a tighttolerance to a graphite rotatable cylinder 30. Glass and graphiteprovide a long working life with low friction without the need forlubrication, while maintaining good sealing.

The passage 46 is open at both ends, including an air inlet end 48corresponding to the gas inlet end 34 of the cylinder. In thoseembodiments that include the alignment apertures 42 in the cylinder 30,the housing 32 includes a second pair of alignment apertures 50 that arediametrically opposed relative to the passage 46. The housing alignmentapertures 50 are positioned to align with the corresponding alignmentapertures 42 in the cylinder 30 when the cylinder 30 is in the “home”orientation, so that a beam of light passing through the alignedapertures 42, 50 can be detected, as described above, to detect the homeposition. In FIG. 3 the closed end 36 of the cylinder 30 has beenomitted so that both openings 50 in the housing 32 are visible. Theapertures 42, 50 may be located anywhere on the cylinder 30 and thehousing respectively. Further, the homing method including the beam oflight as described is merely one possibility. Alternative methods forhoming the cylinder 30 include, but are not limited to, other opticalmethods, magnetic (Hall effect) sensors, etc.

The housing 32 further includes a first opening 52, which is referred toherein as a gas outlet port 52, which terminology should not beinterpreted as limiting. The outlet port 52 is located so as to alignaxially with the tapered cutout 40 of the cylinder 30 when the cylinder30 is installed in the housing 32. The tapered cutout 40 thus provides avariable orifice for the outlet port 52 as the cylinder 30 is rotated inthe housing 32, as best shown in FIGS. 4A and 4B. Due to the variablewidth of the tapered cutout 40 of the cylinder 30, the rotationalposition of the cylinder 30 within the passage 46 controls the effectivearea of the outlet port 52, as best shown in FIG. 4B. The ability toadjust the effective area of the outlet port 52 by rotating the cylinder30 with respect to the housing 32 enables the volumetric gas flow ratethrough the outlet port 52 to be closely controlled. Because the taperedcutout 40 does not extend completely around the cylinder 30, thecylinder 30 can be rotated to an orientation in which the outlet port 52is completely closed. In this configuration, gas can exit the valvethrough an exhaust or bypass opening, as described below.

With reference to FIGS. 3, 4A, and 4B, the housing further includes asecond opening 58 positioned between one of the homing apertures 50 andthe outlet port 52. The second opening 58 may comprise an exhaust orbypass port 58 in certain embodiments. However, the terms exhaust port58 or bypass port 58 should not be interpreted as limiting, as thesecond opening 58 may have other applications, or may not be used atall.

When the cylinder 30 is installed in the housing, the exhaust opening 44of the cylinder is axially aligned with the exhaust port 58 to form anexhaust or bypass passage. The relative positions of the tapered cutout40 and the exhaust opening 44 on the cylinder 30 are selected so thatwhen the tapered cutout 40 at least partially registers with the outletport 52 (i.e. when the outlet port 52 is at least partially open), theexhaust opening 44 of the cylinder 30 is not rotationally aligned withthe exhaust port 58, so that the exhaust port 58 is closed by the solidwall of the cylinder 30. When the tapered cutout 40 of the cylinder 30is not registered with the outlet port 52 (i.e. when the outlet port 52is closed), the exhaust opening 44 of the cylinder 30 registers with (isrotationally aligned with) the exhaust port 58, thereby opening theexhaust port 58 to provide an exhaust or bypass passage for gas flowingtherethrough. This feature enables the valve to be compatible with thosemedical ventilators that use blowers, so that the airflow through thevalve is maintained, even when the outlet port 52 is completely closed.The size and shape of the exhaust passage can be configured so that theblower will be controlled at its best operating point.

The foregoing description of the embodiment of FIGS. 1A-S assumes thatthe direction of gas flow through the valve is as described. However, inalternative embodiments, the direction of gas flow could be reversed.Thus, the outlet port 52 would become a gas inlet, and the inlet end 34of the cylinder would become an outlet.

The present valves can be actuated with a manual knob (not shown) orwith a variety of different motors (not shown) attached to the fitting38 at the closed end 36 of the cylinder 30. Example motors include,without limitation, stepper motors, open loop motors, servo motors(brushless or brushed, with or without encoder) and D.C. brushed motors.A servo motor without an encoder may use some other zero positioningsystem and may use time and/or other parameters, such as flow rate orpressure, for the control loop. The structure of the valves enables verysmall and lightweight valves to be made, which are very easilycontrolled by stepper motors. The selection of a motor may depend uponthe particular application for the valve. Also, when selecting a motorit may be desirable for the motor to be capable of high revolutions perminute (RPM), fine resolution, and/or quick response time. For example,if the valve is to be used with a medical ventilator, it is advantageousfor the motor to be able to quickly ramp up from no flow (to thepatient) to peak flow. Thus, it would be advantageous to select a motorthat provides quick response time and high RPM. Also, in a medicalventilator application, it would be advantageous to select a motor thatprovides high resolution so that the flow through the valve can beprecisely controlled to provide a desired pressure control or volumetricflow control. In various embodiments, flow sensors and/or pressuresensors can be provided to control the motor in accordance withtechniques (such as servo control mechanisms) that are well known, forexample, in the field of medical ventilators.

The present valves exhibit numerous advantages. For example, the valvesenable extremely flexible control. The size (area) of the outlet portcan be adjusted through 300° or more of rotation, enabling very fineadjustment. The sizes of the tapered cutout and the correspondingopening in the housing determine the minimum flow restriction (maximumflow rate), enabling very low pressure drop at high flow rates.

The shape of the taper on the cutout determines the relationship betweenthe change in volumetric flow rate and the change in rotational angle ofthe cylinder. For example, the effective area of the outlet port, andthus the volumetric flow rate through the outlet port at a givenpressure, may vary linearly with the rotational angle of the cylinder,or semi-linearly, or with varying degrees of resolution for differentangles. In the latter example, the cutout may, for example, transitionfrom its maximum width to 20% of its maximum width in the first 100° ofrotation, and then from 20% of its maximum width to closed in theremaining 200°. This type of variable taper provides finer control inthe region of high restriction (200° for 20% overall change).

The structure of the present valves enables rotation in one direction,such as clockwise, for starting at a low flow rate (minimal cutoutwidth) and moving to a higher flow rate (wider cutout width), or viceversa. This functionality affects the response time of the valve fromclosed to open, as very little movement is required to transition fromclosed to fully open. For example, the cylinder may rotate only 20° in afirst direction from closed to fully open while still providing 300° ormore of rotational movement for control. However, if it is desired togradually transition from closed to fully open, the cylinder can berotated in the opposite direction.

When used in connection with a medical ventilator, the valve illustratedin FIGS. 1A-5 is not likely to be used at high pressures. Thus,selection of proper materials enables low inertia, fast response andvery long life without lubrication. For example, in one embodiment thehousing may be glass, or include a glass lining in the cylindricalpassage 46, and the cylinder may be graphite. Both materials areinexpensive and they have matching temperature coefficients. Temperaturewill thus have a small effect on tolerances, keeping the air leaknegligible with little to no friction and wear.

FIGS. 6, 7A, 7B, and 7C illustrate an embodiment of the presentdisclosure that does not include an exhaust or a homing mechanism in thevalve itself. FIG. 6 illustrates an alternative housing 62, which issimilar to the housing 32 of FIGS. 3, 4A, and 4B, but without thealignment apertures 50 or the exhaust port 58. The housing 62 of FIG. 6thus does not provide the homing function described above, and does notenable a bypass flow of exhaust gas. A cylinder for use with the housing62 may similarly omit alignment apertures and/or an exhaust port. Avalve including the housing 62 of FIG. 6 would be most suitable for usein applications that do not need an exhaust port, that do not need ahoming function, or that utilize some other form of homing mechanism notintegrated into the valve itself. In an alternative embodiment, one orthe other of the alignment apertures or the exhaust port may be omitted,while the other is retained.

FIGS. 7A-7C illustrate the cylinder 30 rotatably disposed within thehousing 62 at three different rotational positions. In FIG. 7A therotational position of the cylinder 30 aligns an intermediate widthportion of the tapered cutout 40 at the outlet port 52, enabling amoderate flow rate through the valve. In FIG. 7B the rotational positionof the cylinder aligns a wide portion of the tapered cutout 40 at thevalve outlet, enabling a high flow rate through the valve. In FIG. 7Cthe rotational position of the cylinder aligns a narrow portion of thetapered cutout 40 at the valve outlet, enabling a low flow rate throughthe valve.

In certain embodiments, including some discussed below, two or moretapered cutouts or slots may be provided in a single cylinder to providemultiple variable-orifice outlets, with each outlet having its own flowcharacteristics, thereby providing a separate operational modality foreach gas outlet. For example, in a medical ventilator application, onetapered slot or cutout could provide an outlet for use with adultpatients, while a second tapered slot could provide an outlet forneonates and/or infants, who typically require lower flows and higherrestriction ranges. These embodiments may include an actuator orselector to select which outlet is connected to the patient.

A multi-cutout cylinder 66 for use in a multi-outlet variable orificeflow control valve in accordance with a second embodiment of thisdisclosure is illustrated in FIG. 8. The cylinder 66 is provided with asecond tapered slot or cutout 68 in addition to the first tapered slotor cutout 40. The second cutout 68 is axially spaced from the firstcutout 40 along the length of the cylinder 66. The second cutout 68, inthis example embodiment, may advantageously have a more gradual taperthan the first cutout 40, giving it a narrower width than the firstcutout. In a medical ventilator application, the first cutout 40 may beconfigured to provide desired flow rates and restriction ranges foradults, while the second cutout 68 may be configured to provide desiredflow rates and restriction ranges for infants and/or neonates, whogenerally require lower flows and higher restriction ranges. Thedifferent tapers of the two cutouts provide these varyingcharacteristics.

FIGS. 9 and 10 illustrate a variable orifice flow control valve 10 inaccordance with the second embodiment of this disclosure, in which thecylinder 66 of FIG. 8 is rotatably disposed within a housing 70 thatincludes a gas inlet 71, a first gas outlet 72 and a second gas outlet74. The gas outlets 72, 74 are axially spaced from one another, with thefirst outlet 72 having a location corresponding to the axial location ofthe first tapered cutout 40 on the cylinder 66, and the second outlet 74having a location corresponding to the axial location of the secondtapered cutout 68 on the cylinder 66 (FIG. 8). The second outlet 74 hasan axial length, as measured along the longitudinal axis of the housing70, that may advantageously be less than the axial length of the firstoutlet 72, reflecting the relative widths of the tapered cutouts 40, 68.

FIG. 9 illustrates the cylinder 66 in a rotational position such thatthe first and second outlets 72, 74 are both closed. In thisorientation, an exhaust opening 44 on the cylinder 66 aligns with anexhaust or bypass port 76 in the housing to enable exhaust gas to flowout. FIG. 10 illustrates the cylinder 66 in a rotational position suchthat the first and second outlets 72, 74 are both open, while theexhaust or bypass port 76 is closed. Since the cylinder 66 is configuredsuch that both tapered cutouts 40, 68 align with their respective outletopenings 72, 74 in the housing 70, it is advantageous to couple thevalve of FIGS. 9 and 10 with a selector module for selecting either thefirst outlet opening 72 or the second outlet opening 74. In alternativeembodiments, the exhaust opening 44′ on the cylinder 66 and/or theexhaust or bypass port 76 in the housing may be omitted. The variableorifice flow control valve 10′ may thus be operated with only the twooutlets 72, 74.

As shown in FIG. 8A, in an alternative embodiment, the first and secondtapered slots 40A, 68A or cutouts may be positioned at the same axiallocation on the cylinder 66A, with the first cutout 40A extending over afirst portion of the cylinder's circumference and the second cutout 68Aextending over a second portion of the cylinder's circumference. Byrotating the cylinder 180 degrees, one of the of the cutouts 40A, 68Amay be selectively aligned with a single opening on the housing (notshown) to select the flow range. In this embodiment, the length of eachcutout 40A, 68A is limited by the length of the other cutout 40A, 68A,since the sum of the lengths of the cutouts 40A, 68A cannot exceed thecylinder's circumference. Thus, this alternative embodiment may provideless resolution than the embodiment of FIG. 8. As an example, in certainembodiments, the first cutout 40A may extend between 0°-140° and thefirst cutout 40A may extend between 180°-320°.

FIGS. 11-13 illustrate one embodiment of a selector module 78 (FIG. 13),which can be used with the valve 10′ of FIGS. 9 and 10, or for other gasselection applications. With reference to FIGS. 11 and 12, the selectormodule includes a cylinder 80 (FIG. 11) that is installed for rotationin a housing 81 (FIG. 12) that is similar to the housing 70 shown inFIGS. 9 and 10. The cylinder 80 includes a first cutout or opening 82and a second cutout or opening 84. The cutouts 82, 84 are spaced fromone another axially along the length of the cylinder. The cutouts 82, 84also are spaced from one another along a circumferential angular offset.The housing 81 includes an open outlet end 85, a first opening or cutout86, and a second opening or cutout 88 axially aligned with the firstopening or cutout 86, and located between the first opening 86 and theoutlet end 85.

The axial positions of the cutouts 82, 84 in the cylinder 80 correspondto the axial positions of the cutouts 86, 88 in the housing 81. Thus,given the angular offset of the cutouts 82, 84 in the cylinder 80, therotational position of the cylinder 80 relative to the housing 81selectively aligns either the first cylinder cutout 82 with the firsthousing cutout 86 to form a first module inlet (FIG. 13), or the secondcylinder cutout 84 with the second housing cutout 88 (FIG. 14) to form asecond module inlet. Both module inlets cannot, however, be openedsimultaneously. The selector module 78 can thus be used to selectbetween a first module inlet 92 formed by the aligned first cutouts 82,86 (FIG. 13) and a second module inlet 94 formed by the aligned secondcutouts 84, 88 (FIG. 14), with an open end of the cylinder 80 and theopen outlet end 85 of the housing forming a module outlet 90.

With reference to FIG. 16, a selector module 78A, which is similar tothe selector module 78, can be inverted so that a first module inlet 92Aaligns with the first outlet 72 in the valve housing 70, and a secondmodule inlet 94A aligns with the second outlet 74 in the valve housing70. The selector module 78A can thus be used to select between the valveoutlets 72, 74 by changing the rotational orientation of the cylinderwithin the selector module housing 81A. The rotational orientation ofthe cylinder can be changed with, for example, a stepper motor (notshown) or a manual knob (not shown).

With reference to FIG. 15, the module cylinder can be rotated to providevarying degrees of partial opening of the first and second module inlets92, 94, respectively. Thus, the degree to which the module inlets 92, 94are selectively opened can be used to control the rate of gas flowthrough the selector module 78. For example, FIG. 15 illustrates theselector cylinder 80 in a rotational orientation within the housing 81such that the second module inlet 94 is partially open. Anotherrotational position (not shown) of the selector cylinder 80 can providea partial opening of the first module inlet 92. The selector module 78can thus perform the dual tasks of selecting a single module inlet andcontrolling the flow rate through the selected inlet. Furthermore, thedirection of gas flow through the selector module 78 can be reversed ifdesired, so that the module outlet 90 functions as an inlet, and thefirst and second module inlets 92, 94 function as first and secondselectable module outlets, respectively. In alternative embodiments (notshown), the selector module may have more than two inlets that may beselectively opened and they can be tapered.

FIGS. 17-21 illustrate additional embodiments of the present valves thatare particularly suited for gas mixing or blending applications. FIG. 17illustrates a rotational valve element or cylinder 96 having an openoutlet end 97, a first tapered slot or cutout 98 extending partiallyaround the circumference of the cylinder, and a second tapered slot orcutout 100 extending partially around the circumference of the cylinderbetween the first cutout 98 and the open outlet end 97. The cutouts 98,100 are axially spaced from one another, and each has the same taperprofile. However, in alternative embodiments the cutouts 98, 100 couldhave different taper profiles. In the illustrated embodiment, thecutouts 98, 100 have reverse orientations, such that the first cutout 98increases in width in a first circumferential direction around thecylinder 96, while the second cutout 100 decreases in width in the firstcircumferential direction around the cylinder 96. Furthermore, the firstand second cutouts 98, 100 have respective vertices 99, 101 that arepositioned on diametrically opposite sides of the cylinder 96. Asfurther described below, the illustrated geometry of the cylinder 96creates advantages for mixing two gases from two sources, such as airand O₂ in a medical ventilator application, or warm air and cold air ina vehicle heater application.

FIG. 18 illustrates a housing 102 defining a cylindrical chamber havingan open end 104 for receiving the cylinder 96. The housing furtherincludes a first inlet opening 106 and a second inlet opening 108located between the first inlet opening 106 and the open chamber end104. The inlet openings 106, 108 are spaced from one another along alongitudinal axis of the cylindrical chamber, and they are positioned tocorrespond to the axial positions of the tapered cutouts 98, 100 in thecylinder 96 when the cylinder 96 is installed in the chamber of thehousing 102. A valve outlet 116 (FIG. 19) is provided by the open outletend 97 of the cylinder 86 and the open end 104 of the housing chamber.

FIGS. 19-21 illustrate a variable orifice gas mixing or blending valve114, comprising the cylinder 96 installed in the housing 102, asdescribed above. Changing the rotational orientation of the cylinder 96within the housing 102 enables adjustment of the flow restrictionthrough a first inlet port 110 and a second inlet port 112 in the valve114. The first inlet port 110 is formed by the alignment of the firstcylinder cutout 98 with the first inlet opening 106 of the housing, andthe second inlet port 112 is formed by the alignment of the secondcylinder cutout 100 with the second inlet opening 108 of the housing102. The mixture of gases flowing through the outlet 116 of the valve114 can thus be adjusted by changing the rotational orientation of thecylinder 96 within the housing 104. For example, in FIG. 19, both inletports 110, 112 are open approximately the same amount, so thatapproximately equal amounts of a first gas and a second gas will bemixed inside the cylinder 96 and then exit the outlet 116. In FIG. 20,the first inlet port 110 is closed, while the second inlet port 112 isopen. Thus, the gas flowing through the outlet 116 will contain only thegas flowing through the second inlet port 112. In FIG. 21, the firstinlet port 110 is slightly open, while the second inlet port 112 is morefully open. Thus, the gas flowing through the outlet 116 will contain arelatively small quantity of the gas flowing through the first inletport 110 and a relatively large quantity of the gas flowing through thesecond inlet port 112.

The geometry of the cylinder 96 creates advantages for mixing two gasesfrom two sources, with one gas entering the cylinder 96 through each ofthe inlet ports 110, 112. Because the vertices 99, 101 of the cutouts98, 100 are located on opposite sides of the cylinder 96, and becausethe cutouts 98, 100 increase in width in opposite directions around thecylinder's circumference, rotating the cylinder 96 in a first directionwithin the housing 102 will increase the effective orifice area of oneof the inlet ports, while at the same time decreasing the effectiveorifice area of the other inlet port. The percentages of each gas in themixture flowing through the outlet 116 can thus be adjusted by rotatingthe cylinder 96 in one direction or the other. In some embodiments thetapered cutouts 98, 100 may have different rates of taper. Exampleapplications for such embodiments include those where the proportion ofeach of the constituent gases may be varied within some range smallerthan 0%-100%, or where one gas is at a higher pressure than the other,which would require a smaller sized orifice for the same gas flow.

In alternative embodiments, the degree of control over the percentagesof each gas in the mixture may not need to be very precise. In suchembodiments the tapered cutouts 98, 100 on the cylinder 96 could bereplaced with, for example, a plurality of discrete openings (not shown)having different sizes. The discrete openings could be positionedwherever needed on the cylinder to enable adjustments of the relativeamounts of each gas being mixed. Furthermore, in alternativeembodiments, additional inlets may be provided for mixing any number ofgases. The illustrated embodiment showing mixing of two gases should notbe construed as limiting.

FIGS. 22, 23A, and 23B illustrate additional embodiments of the presentvalves that are particularly suited for directional blowing of air inroom or vehicle ventilation (e.g., heating/cooling) applications. FIG.22 illustrates a valve 126 comprising a cylindrical housing 118 thatrotatably receives a cylinder 120. Both the housing 118 and cylinder 120are open at a first end comprising an airflow inlet 121. The housing 118includes a cutout 122 (preferably, but not necessarily, rectangular inshape) that extends over a certain percentage of the housing'scircumference, for example, 50%. With reference to FIGS. 23A and 23B,the cylinder 120 includes an opening 124 (preferably, but notnecessarily, rectangular in shape) that forms an airflow outlet. Byrotating the cylinder 120 within the housing 118 such that the opening124 in the cylinder 120 remains in the region of the cutout 122 in thehousing, the direction of airflow through the valve 126 can be changed.Further, by rotating the cylinder 120 within the housing 118 such thatthe cutout 124 in the cylinder 120 is covered by the housing, airflowthrough the valve 126 can be blocked. The valve 126 may thus serve asnot only a flow director, but also an on/off mechanism.

In alternative embodiments, a flow control cylinder, such as that shownin FIGS. 1A-2C, for example, may be provided inside the directionalvalve of FIGS. 22, 23A, and 23B. FIG. 24 illustrates such an embodiment.In this embodiment, both the direction and the amount of air flow can becontrolled by the same valve system. Such an embodiment can comprise asingle system direction and flow control valve for an automobile airconditioning system, for example, where the user can electronicallyadjust the amount of flow for a specific outlet as well as the directionof flow.

FIGS. 25-28 illustrate another embodiment of a selector module for usewith the present valves. The selector module is particularly suited foruse in a medical ventilator application. Thus, the following descriptionwill reference such an application. However, as will all embodimentsdescribed herein, references to particular applications should not beinterpreted as limiting.

The selector module includes a cylindrical valve element (“cylinder”)130 (FIGS. 27 and 28) that is installed for rotation in a housing 132.The cylinder 130 includes a first cutout or opening 134, a second cutoutor opening 136, and a third cutout or opening 138. The cutouts 134, 136,138 are spaced from one another axially along the length of the cylinder130. The cutouts 134, 136, 138 also are spaced from one another along acircumferential angular offset, which is described further below. Withreference to FIG. 28, the cylinder 130 includes a closed end 140 and anopen end 142, or flow outlet end 142. A motor or other drive apparatus(not shown) may engage the closed end 140 in a similar manner asdescribed above with respect to the previous embodiments.

As described further below, the cutouts 134, 136, 138 correspond tocutouts or openings in the housing 132. With reference to FIG. 27, thefirst cutout 134 comprises an exhaust opening. The exhaust opening 134extends diametrically through the sidewall of the cylinder 130. In otherwords, the exhaust opening 134 (the opening that is nearest the viewerin FIG. 27) includes diametrically-opposed cutouts 134, 134 a in thesidewall of the cylinder 130. With reference to FIG. 27, the secondcutout 136 comprises a first selector opening configured for adult flowrates, and the third cutout 138 comprises a second selector openingconfigured for neonate flow rates.

FIGS. 25 and 26 illustrate the housing 132 in separate sections for easeof description. The housing can be constructed from multiple sections,or as one integral piece. The housing 132 includes a cylindricalreceptacle 144 sized to receive the cylinder 130, similarly to theabove-described embodiments. The receptacle 144 includes a reduceddiameter at an open outlet end 146, thereby creating a transverseannular shoulder 148 against which the cylinder 130 may bear. Atransverse annular shoulder may similarly be provided in any of thepresent embodiments.

With reference to FIG. 25, the housing 132 further includes a firstopening or cutout 150, a second opening or cutout 152, and a thirdopening or cutout 154. The cutouts 150, 152, 154 are all axially alignedwith one another and located between the outlet end 146 and a secondopen end 156 of the housing 132. The first opening 150 extendsdiametrically through opposed sidewalls of the receptacle 144. In otherwords, the cutout 150 in FIG. 25 includes diametrically-opposed cutouts150, 150 a in FIG. 26.

The axial positions of the cutouts 134, 134 a, 136, 138 in the cylinder130 correspond to the axial positions of the cutouts 150, 150 a, 152,154 in the housing 132. Further, the selector module is configured toabut a valve, similar to the valve 10′ of FIGS. 9 and 10, so that theaxial positions of the cutouts 150, 150 a, 152, 154 in the housing 132correspond to the axial positions of cutouts in the valve. The selectormodule can thus be used to select between adult and neonate flow ratesby changing the angular orientation of the cylinder 130 within thehousing 132. Given the angular offset of the cutouts 134, 134 a, 136,138 in the cylinder 130, the rotational position of the cylinder 130relative to the housing 132 selectively aligns either the first cylindercutout 134, 134 a with the first housing cutout 150, 150 a to form anexhaust outlet, or aligns the second cylinder cutout 136 with the secondhousing cutout 152 to form a first selector inlet for adult flow rates,or aligns the third cylinder cutout 138 with the third housing cutout154 to form a second selector inlet for neonate flow rates. Bothselector inlets cannot, however, be open simultaneously. The selectormodule can thus be used to select between an exhaust outlet formed bythe aligned cutouts 134, 134 a, 150, 150 a, a first module inlet formedby the aligned cutouts 136, 152, and a second module inlet formed by thealigned cutouts 138, 154, with the open end 142 of the cylinder 130 andthe open outlet end 146 of the housing forming a module outlet.

Advantageously, with reference to FIGS. 27 and 28, the cylinder 130includes an interior partition wall 156. The partition wall 156 islocated axially between the first openings 134, 134 a and the secondopening 136. The partition wall 156 thus further separates airflow tothe patient from exhaust airflow.

Another advantage of the configuration of the cylinder is the smallangular offsets between the cutouts 134, 136, 138. With reference toFIG. 27, there is very little angular separation between the firstcutout 134 and the second cutout 136, and between the first cutout 134and the third cutout 138. The angular separation between the secondcutout 136 and the third cutout 138 is substantially equal to the widthof the first cutout 134, which is located between the second and thirdcutouts 136, 138 in the circumferential direction.

The close angular spacing between the cutouts 134, 136, 138 enables fastresponse times. For example, a 30° rotation may move the selector fromthe adult setting, past the exhaust setting, to the neonate setting. A15° stepper motor would then require only two steps to transitionbetween the three settings. Only coarse resolution is required in suchan application, as the selector module is essentially just an on/offswitch. It is believed that the selector module can transition betweensettings in as little as 2 milliseconds.

In certain applications, smaller steps can enable a small flow to themain outlet, while most of the flow goes to the exhaust. An example ofsuch an application where this functionality is useful is positiveend-expiratory pressure (PEEP) flow in ventilation.

The selector module of FIGS. 25-28 enables a separate valve to remain ata desired setting instead of it having to move many steps to reach theproper angular orientation from its closed position. The open/closeaction can be performed by the selector, enabling fast transition fromclosed to fully open. The selector module also provides an adult/neonateselector.

The present embodiments are not limited to the structural configurationsshown in the figures. In particular, certain structural features, suchas locations of openings, may be reversed. For example, while FIGS. 1-4show a tapered opening 40 in the cylinder 30, and a rectangular opening52 in the housing 32, the opening in the cylinder could be rectangularand the opening in the housing could be rectangular. Similarly, whilethe openings 40, 44 in the cylinder 30 are circumferentially spaced fromone another and the openings 52, 58 in the housing 32 are located on acommon face of the housing 32, these configurations could be reversed,i.e. the openings in the cylinder could be located at the samecircumferential position on the cylinder, while the openings in thehousing could be spaced from one another in a direction perpendicular toa longitudinal axis of the housing, and could even be in separate facesof the housing.

The above description presents the best mode contemplated for carryingout the present invention, and of the manner and process of making andusing it, in such full, clear, concise, and exact terms as to enable anyperson skilled in the art to which it pertains to make and use thisinvention. This invention is however, susceptible to modifications andalternate constructions from that discussed above that are fullyequivalent. Consequently, this invention is not limited to theparticular embodiments disclosed. On the contrary, this invention coversall modifications and alternate constructions coming within the spiritand scope of the invention as generally expressed by the followingclaims, which particularly point out and distinctly claim the subjectmatter of the invention.

What is claimed is:
 1. A gas flow control system comprising: a blowertype medical ventilator for ventilating patients; and a control valvefor use in the ventilator, the control valve comprising: a valve housingcomprising a hollow cylindrical open-ended interior passage, and notmore than one housing opening formed in a wall of said housing, whereinat least the interior passage of said valve housing is made of or linedby glass; and a cylindrical valve element comprised of graphite, thevalve element comprising a valve element inlet and not more than onetapered opening in a wall thereof; wherein the cylindrical valve elementis rotatably received within the interior passage of the valve housing,such that an area of overlap of the housing opening and the taperedopening of the cylindrical valve element forms a single outlet, the sizeof which is varied by rotation of the cylindrical valve element withinthe interior passage of the valve housing, thereby obtaining aproportional flow valve; and wherein when said housing opening and saidtapered opening are at least partially aligned, gas, delivered to saidcontrol valve, exits said single outlet.
 2. The gas flow control systemof claim 1, wherein the valve element is open at a first end and closedat a second end opposite the first end.
 3. The gas flow control systemof claim 1, wherein when said housing opening and said tapered openingare non-aligned and gas is delivered to said control valve, said gasflow control valve is configured to prevent gas exit.
 4. A gas flowcontrol system comprising: a blower type medical ventilator forventilating patients; and a control valve for use in a ventilator, thecontrol valve comprising: a valve housing comprising a hollowcylindrical open-ended interior passage, and not more than one housingopening formed in a wall of said housing, wherein at least the interiorpassage of said valve housing is made of or lined by glass; and acylindrical valve element comprised of graphite, the cylindrical valveelement comprising a valve element inlet and a first and a secondtapered opening in a wall thereof; wherein the first and second taperedopenings are located at a same axial position along a length of thevalve element, and wherein the second tapered opening has a narrowerwidth than the first tapered opening; wherein the cylindrical valveelement is rotatably received within the interior passage of the valvehousing, such that an area of overlap of the no more than one housingopening and the first or second tapered opening of the valve elementforms a single outlet of the control valve, the size of which is variedby rotation of the cylindrical valve element within the interior passageof the valve housing, thereby obtaining a proportional flow valve whoseflow range depends on which of the two tapered openings aligns with thesingle outlet on the housing.